Interpretive Summary: Sunflowers are native to North America and thus the associated insects have coevolved with the plants. The objective of this project was to survey the insect fauna of native sunflowers in the central and northern Plains. We collected heads containing banded sunflower moth larvae and stalks containing sunflower stem weevil larvae to identify larval parasites and determine whether or not they are currently present in cultivated sunflower. Insect numbers were compared to locate sunflower populations with lower insect densities as sources of germplasm that could potentially provide resistance genes. Collections of native sunflowers in North and South Dakota and in six states in the northern and central Plains recovered larvae of the banded sunflower moth and sunflower stem weevil larvae, respectively. Larvae were present in all locations. There was a trend for higher densities of banded sunflower moth larvae from west to east in both North and South Dakota. The average number of sunflower stem weevil larvae per stalk increased as latitude decreased. The variation in larval numbers among native sunflower populations indicates the potential for genes offering resistance to both insect species. Parasites reared from larvae in the native sunflowers all have been previously reported to occur in cultivated sunflower. However, their presence also shows that wild sunflowers act as a reservoir for natural enemies of insects that are pests of commercial sunflower. The search for new parasitoids in the future will include additional sites within the same latitudes and locations farther south and west. Additional collections may locate parasites that could eventually provide improved biological control in cultivated sunflower.

Technical Abstract:
Sunflowers are native to North America and thus the associated insects have coevolved with the plants. The objective of this project was to survey the insect fauna of native sunflowers in the central and northern Plains. We collected heads containing banded sunflower moth larvae and stalks containing sunflower stem weevil larvae to identify larval parasites and determine whether or not they are currently present in cultivated sunflower. Insect numbers were compared to locate sunflower populations with lower insect densities as sources of germplasm that could potentially provide resistance genes. Collections of native sunflowers in North and South Dakota and in six states in the northern and central Plains recovered larvae of the banded sunflower moth and sunflower stem weevil larvae, respectively. Larvae were present in all locations. There was a trend for higher densities of banded sunflower moth larvae from west to east in both North and South Dakota. The average number of sunflower stem weevil larvae per stalk increased as latitude decreased. The variation in larval numbers among native sunflower populations indicates the potential for genes offering resistance to both insect species. Parasites reared from larvae in the native sunflowers all have been previously reported to occur in cultivated sunflower. However, their presence also shows that wild sunflowers act as a reservoir for natural enemies of insects that are pests of commercial sunflower. The search for new parasitoids in the future will include additional sites within the same latitudes and locations farther south and west. Additional collections may locate parasites that could eventually provide improved biological control in cultivated sunflower.